Genetics
and DNA Technology: Legal Aspects, by Wilson Wall
Cavendish
Publishing, 2004 (2nd Ed). ISBN 1859418937
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| DOI: 10.2966/scrip.020305.410 | ||
This book aims to bridge an often-perceived gap between legal and
scientific texts. Primarily intended for lawyers, law students and
professionals with little or no scientific training, this book is
written by a geneticist with considerable court experience. Drawing
together the advances in DNA technologies and procedures, there is no
assumption of prior knowledge in the field. This is an ideal
starting point, from which a reader’s understanding of other,
more technical resources will be vastly improved.
The overlap between law and science is ever increasing. Lawyers and
judges alike must be aware of the pertinent issues, and generally
more than the rudimentary basics, of biology, genetics and basic
chemistry. In addition, practitioners must also be sufficiently
familiar with statistics in order to interpret the findings in
today’s multidisciplinary approach to identification. The
application of DNA technologies to both criminal and civil
investigations is addressed. At the most basic level, crime scene
analysis generally relates to an unknown suspect and in civil cases,
paternity testing will have one, or possibly more, known comparison
samples. The choice of technology is influenced by the type of
investigation and the limitations of each must be appreciated in
order to present forensic evidence appropriately.
The first chapter covers the historical background to personal
identification. Starting with the problems of accuracy and precision
associated with the basic anatomical measurements known as
Bertillionage, the progression of fingerprinting in the 20th
century is discussed and the principles of basic blood grouping are
presented. This introduction explains clearly why DNA technology is
presented as the method of choice with a high discriminatory power,
able to identify an individual within a higher degree of certainty
from a large population of potentially matching candidates.
The notion of an ‘ideal sample’ is then considered in
relation to forensic sampling, which is often overlooked in legal and
scientific texts. The types of error, whether deliberate, inherent
or accidental are all significant to the interpretation of evidence.
These terms are presented plainly and accompanied by practical,
useful examples. With an increased technological ability to amplify
DNA from even a single cell, the potential for errors and mistakes is
acknowledged, although further discussion or criticisms are needed to
drive this message home, especially to the novice reader. Sample
contamination and degradation are presented as fundamental issues
which should be understood by all professionals who may only be
remotely involved in sampling.
In the third chapter, the book returns to ABO, Rhesus and other blood
groupings. Even though they are genetically derived, the use of
blood analysis provides little information for positive, unique
identifications. Mass screening, a cheap and speedy means to narrow
down a large group of possible suspects, is the ideal situation for
using these techniques to exclude numerous potential candidates.
Although there is little probative value in traditional blood
analysis, the text adequately describes the basic concepts to the
reader. Certainly the use of diagrams in this, and subsequent
chapters, would have been an ideal enhancement to a second edition to
illustrate the patterns of inheritance. For the novice reader, the
use of visual representation, so commonly found in biochemistry
textbooks, is lacking which may hinder their understanding of some
simple yet integral concepts. For a more advanced audience, the lack
of discussion regarding innovative research techniques throughout the
text may be disappointing.
The fourth chapter analyses the DNA technologies one would expect in
today’s laboratories, and describes four approaches to
extracting information from the variable regions of DNA. Firstly,
the length of DNA fragments can be measured, once they have been
restricted, or broken down into shorter pieces, using a variety of
enzymes. Termed, RFLP (restriction fragment length polymorphisms),
this process is criticised for the use of subjective measurements and
uncontrollable variables. The use of multi-locus probes is described
to increase the discriminatory power of this technique. Conversely,
the second approach examines the variation within specific genes,
which is less subjective: an indication of presence or absence is
clearly expressed, although the discriminatory power is significantly
lower. Again, descriptions such as the polymerase chain reaction
(PCR) would be greatly improved with the use of diagrams, despite an
interesting analogy between base sequences and knitting patterns.
The third approach is the system of choice, making use of the
variation in short tandem repeats. This has the added ability to
differentiate samples based on sex although it is noted that
contamination, a recurring theme in the book, is a serious source of
error. Lastly, the direct analysis of base sequences is a technique
envisaged for future forensic identification procedures. Single
nucleotide polymorphism or ‘snip’ analysis, aided by the
Human Genome Project, may perhaps yield physical characteristics of
crime scene suspects, such as natural hair colour, nose shape or
physical build. This futuristic approach to criminal investigations
may be far on the horizon, however the redundancy of current ‘short
tandem repeat’ databases for this technique is a valid point.
As technology develops, the reliance upon our current and highly
valued criminal justice databases may prevent the uptake of new
techniques that employ different arrays of data.
The fifth chapter builds upon the basics already established to
illustrate how the type of question influences the value of the
answer. The use of statistics is pivotal. The null hypothesis,
likelihood ratios and Bayesian prior probabilities are explained,
although by this stage the true novice reader may well be lost.
Reference to case law is limited throughout, occasionally citing
Nature rather than the traditional law reports one would
expect. This does have the benefit of providing the reader with a
more scientific discussion of technology, which can then be read, if
required, in conjunction with the more familiar law reports.
The final three chapters are brief and fail to comment on the more
significant developments concerning DNA databases, cloning and
genetic profiling. Disappointingly, there is little expansion or
significant difference between this and the first edition from 2002.
The plethora of new techniques and future technologies for the
medical profession have already begun to require legal interventions
in regulating the development of genetic research and will continue
to do so. Whilst the preceding chapters provide the building blocks
of legal aspects to DNA technologies, the title of the book may be
somewhat misleading if the reader expects a comprehensive approach to
all forms of technology.
In summary, this book provides a basic overview of the main
techniques in traditional DNA analysis. The lack of academic weight
may appeal to lawyers with little or no scientific grounding who wish
to catch up with the ever-increasing pace of genetic research. The
legal aspects of DNA technologies, in this text, are restricted to
paternity testing and criminal identifications. The author devotes
little attention to the medico-legal developments in therapeutic
cloning and research, which is undoubtedly covered in other texts,
but remains a significant failing in this edition.
Michael Bromby
Joseph Bell Centre for Forensic Statistics and Legal Reasoning
Glasgow Caledonian University